1. Field of the Invention
The present invention relates to the field of touch sensitive technology, and more particularly, to a touch sensitive technique with which reduces cyclical electromagnetic interference (EMI).
2. Description of the Prior Art
Consumer electronic products have already been necessities of modern life. Such as tablet computers, mobile phones, and other electronic devices, most of them use the touch sensitive screen as their main input/output interface. In addition, they are also configured with WiFi wireless networking devices, such as Bluetooth devices, individual short-distance wireless communication devices, the third or fourth generation of mobile communication network equipment, wireless charging devices, global positioning systems (GPSs), and so on. These wireless devices require to equip antennas in their thin, short, and limited device bodies. When these antennas transmit or emit signals, they will cause electromagnetic interference (EMI) with each other.
For example, a projected capacitive touch sensitive screen which is commonly used now, and the touch sensitive controlling device thereof typically adopts mutual-capacitive detection. It commands a part of or all of electrodes to emit driving signal in order to detect the external conductive object(s) approaching or approximating the touch sensitive screen. The emitted driving signal and the signal related to the resonance frequency of the driving signal will cause electromagnetic interference with other antennas and wireless devices in the same electronic device.
Furthermore, in some situations, when the touch sensitive controlling device provides the driving signals to the electrodes, there is usually a certain time interval between each two of the driving signals, or the touch sensitive controlling device emits the driving signals cyclically. However, compared to those random noise signals, these cyclical driving signals (may also be referred as cyclical interference signals sometimes), to some communication systems, may further block or interfere with information transmission. In certain cases, for example, the spreading spectrum communication systems have a stronger resistance to or anti-interference with white noise.
Accordingly, there is a requirement for a touch sensitive controlling device, system, and controlling method thereof that reduce cyclical electromagnetic interference with.